TNF-alpha is an independent serum marker for proliferative retinopathy in type 1 diabetic patients

This study aimed to determine if there are any associations between serum levels of inflammatory markers and proliferative retinopathy (PDR) in type 1 diabetic patients.

A cross-sectional design was utilized for this study.

One hundred twenty-eight type 1 diabetic patients underwent stereo fundus photography according to the Early Treatment Diabetic Retinopathy Study and were divided into two retinopathy groups: no or nonproliferative retinopathy (NDR/NPDR; n=62) and PDR (n=66). Serum levels of tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1 beta, IL-6, soluble vascular cellular adhesion molecule-1 (sVCAM-1), soluble intercellular adhesion molecule-1 (sICAM-1), P-selectin, and high-sensitivity C-reactive protein (hsCRP) were analyzed. Statistical analysis was performed using nonparametric Mann-Whitney U test and multivariate logistic regression analysis.

Patients with PDR had higher levels of TNF-alpha [7.0 pg/ml (<4-17) vs. 6.0 pg/ml (<4-25); P=.009], sVCAM-1 [860 ng/ml (360-2120) vs. 700 ng/ml (310-1820); P<.001], and P-selectin [180 ng/ml (39-400) vs. 150 ng/ml (42-440); P=.017; figures are expressed as median (range)]. There were no differences in serum levels of sICAM-1 or hsCRP. IL-1 beta was not detectable in any patient, and IL-6 was detectable in only 22.7% of the patients. In multivariate logistic regression analysis, TNF-alpha was the single, persistent, independent determinant inflammatory marker for PDR.

The association between TNF-alpha and PDR in type 1 diabetic patients suggests that inflammation might play a role in the pathogenesis of proliferative diabetic retinopathy.